So in my attempt to fix, when removing the damaged R509 resistor, I guess I pulled out the solder pad on one of the holes (the hole closest to Q503). Now solder will not stick when soldering a new resistor back in. After doing some research, folks fix this using a few techniques, from soldering to the next available spot, or to the trace, or using a jumper. Can anyone recommend which repair method might be best in this case?

Thanks all for the amazing information on this thread - I was able to resurrect my beloved IL-60 sub-woofer on the left hand speaker. It's almost 10 years ago that the first post was made, so I'm glad it's still alive on the internet!

I had an unusual problem - the light on the front volume control worked OK (red on standby, green when a signal detected), however there was no sound output from the sub.

After pulling the speaker apart, I found this thread and immediately noticed that my R509 was a little dark, in fact the yellow band was almost gone. It measured 120K, so no too far off, but it got replaced anyway:

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However this didn't fix the problem, so I started troubleshooting using one of the bulletins in the service manual (Service Bulletin INF2001-04 Rev2 – May 2005). I didn't quite like the resistance measurements I was seeing fo I changed all the MOSFETs (Q501, Q502 are IRF740, and Q504/507 are IRF640) - I ordered replacements from digikey.com, after which they measured just right. The circuit has capacitors on it, so measurement takes a couple of seconds to stabilize.

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But it still didn't work... Aaargh, so I had to pull up the circuit diagram and follow it carefully with a multi-meter. I noticed that while Q504/507 were getting plenty of input power, they were never turning on. The service bulletin says that there should be about 10-20V nominal power on the CD+- rails (that connects to the amplifier plate). The part that drives this circuit is the BASH hybrid IC: HC1011.

I took a close look using a flashlight, and what do you know - a hairline crack on the board?! I wonder if this is common, or if mine just had a defect?

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I probably could have fixed it using some superglue and carefully re-soldering the broken tracks, but I was able to find a replacement by calling Infinity/Harman. Here's the details from the live chat session:

The part that you need is still available in our warehouse. Yo can call us to this number (877) 871-6755 to place your order. because we cannot process an order through chat. Price, including shipping: $32.34

So I ordered one by calling this number - I asked them for part HC1011 and they found it right away. I also found on by searching google shopping on aliexpress.com, was $40 from China, so if you're in the USA the best bet is direct from Infinity/Harman.

After replacing it, I now get 18V on the CD+- power rails, just like I was supposed to. I also ran through the steps for re-biasing the output MOSFETS (see IL60 ADJUST BIAS PROCEDURE in the service manual), I marked the positions of R11 & R27 with a sharpie before turning them counter clockwise, they were almost exactly right so this step was probably not necessary.

Powered it all up, but still no bass. But now I'm getting a proper signal output on the speaker lines (which wasn't there before). If you put the multi-meter into AC Volts, should see movement every time a bass drum is hit So I followed the cables through the insulation and saw that one was unplugged, possibly accidentally yanked out during back plate removal. Plugged it back in, and voila, I can feel the bass again!

Thanks again to all the posters for the great info in this thread![/img]